Picture projecting machine



Sept. 22, 1942. J. GUERCIO PICTURE PROJECTING MACHINE Filed Dec. 5, 1940 2 Sheets-Sheet l fire/15072 Z0 Jose vi 'zzer'dz'a,

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Sept. 22, 1942. GUERCK) 2,296,344

' PICTURE PROJECTING MACHINE Filed D80. 5, 1940 2 Sheets-Sheet 2 I fry-J1 1 22 21 we; .7% M 6% 05 iizarrzey,

Patented Sept. 22,

UNITED}.- STATES PATENT OFFICE k I morons "(time moms Application December 5,( No. 368,569

BCIaIms.

This invention relates to picture projecting machines and more specially to a machine for the projection of a series of still pictures from a film to advance the film one picture or panel at each intermittent operation for still exposure at each interval between such operations and so that the duration of exposur may be as long or as short as desired, say seven seconds or the period cut in half to threev and one-half seconds by way of example.

Another object of the invention is to provide an improved picture projecting machine or, device for the projection of a succession of still pictures from a continuou strip film with relatively short periods of time between exposures so that a certain number of pictures, panels or frames may be exposed in a given period of time, say 130 pictures or frames in liminutes for exhibiting to audiences, window display and the like so that certain information may bebrought before the public eye.

Another object of the invention is to provide a novel and simple film gate by which the film is exposed to the lightray for projection upon a screen at the film aperture which permits the film to be easily fed into position and which will pass the joint where the ends of a strip are overlapped to form a continuous film or at any point in the length thereof so that the film will not be disrupted or broken'at the: joint in moving through the gate.

Another object of the invention is to provide a novel picture projector in which the mechanism is mounted a a unit almost in its entirety upon a single wall or plate to facilitate and simplify the manufacture and assemblage thereof and to render the parts more readily accessible than heretofore, and in which the working parts are, with the exception of the electrical contrivances, including the driving motor, Geneva or star wheel movement and a cooling fan and its motor, all exposed at one side of the wall or panel and in which said wall or panel is adapted to form a closure for one side of a case in which the other parts f the device are mounted in a substantially box like structure having a switch controlling an electrical circuit for the operation thereof which, however, may be in the form of an extension cord with a switch for remote control and which may be connected to a source of electrical energy by plugging into a wall socket or house wiring at any convenient point.

Still another object of the invention is to provide a novel arrangement for causing a continuour. movement of cool air through the machine and particularly around the light source and the film at the film gate where the film is particularLv subject to friction so as to reduce the temperatures at these points and eliminate the hazards or dangers of combustion or fire.

Still another object of the invention is to mount the parts and mechanism, including the case and its plate or wall forming a side or panel for carrying the mechanism in such a way as to arrange the parts ina relation to render them more accessible and facilitate manufacture.

Another object of the invention is to provide novel means for removing dust or foreign matter from the film during its travel and prior to passing into the film gate for exposure and projection of the picture or advertising matter thereon, said means including brushes adjacent the film gate and a felt or other cleaning pad mounted on an extension of the bottom or base of the machine constituting a part of the case which may be provided with suitable means for mounting the machine on a tripod, if desired, although it may be mounted upon any other suitable elevated support for use.

Further objects and advantages will appear and 'be brought out more fully in the following specification, reference being had to the accompanying drawings, in which:

Fig. 1 is a side elevation ofa picture projecting machine in accordance with an embodiment of my invention, the same being shown partlyw broken away and in section Fig. 2 is a transverse sectional elevation taken on the line 2-2 of Fig. 1 but looking at th front end of the objective lens assembly;

Fig. 3 is an enlarged fragmentary vertical seetional elevation of the film gate structure;

Fig. 4 is a horizontal sectional view taken on the line 4-4 0fFig.3;

Fig. 5 is a front elevation looking at one side of a fixed aperture plate constituting a part of the film gate and showing a section of a film strip in position; I

Fig. 6 is an inside elevation of a springv pressure aperture plate also forming a part of the film gate;

Fig. 7 is an inside elevation of a pressure spring forming part of the film gate;

Fig. 8 is a vertical sectional elevation taken longitudinally on the line 8-4 of Fig. 2;

Fig. 9 is a horizontal sectional view taken on the line !--8 of Fig. 8 with the lamp in elevation Fig. 10 is a transverse vertical sectional view taken ontheline Iii-"01118.8;

Fig. 11 is a fragmentary vertical sectional elevation showing the latch fastening for the cooling chamber hood for the lamp;

Fig, 12 is a detailed elevation showing the cam and operating arm of the Geneva or star wheel movement; and

Fig. 13 is an elevation of a double or cross arm for the Geneva or star wheel movement.

Referring more particularly to the drawings, the picture projecting machine is shown as comprising a front wall or plate i which forms a vertical side or panel for a box or case It of relatively rectangular form with the panel running longitudinally thereof. This panel forming wall or plate which mounts the mechanism unit of the device is removably secured in position against a pair of angle members H at the vertical front edges or corners of the case or box within the walls thereof and particularly the side walls I! viewing the panel facewise, which form the front and rear of the case as by screws l9 passing through suitable apertures in the wall I5 and threaded apertures in the angle members H at their inwardly projecting flanges. The back of the case is designated at and may be in the form of an open wall formed with or separate from the walls I! and a top wall 2|, which latter is provided with a rectangular or other opening 22. A handle 23 is provided on the top wall and is shown spanning the opening 22. A bottom wall or base is designated at 24 and is provided with a front or base extension forming a plate 25 for a purpose to be hereinafter made apparent. The bottom wall or base may be provided with suitable means for mounting the device upon an easel or other horizontal support in an elevated position for projecting the pictures or advertising matter upon a suitable screen placed at a proper distance therefrom.

As before stated, the front panel formed by the wall or plate l5 mounts a unit of the device constituting primarily the film carrying and picture projecting mechanism which, for the most part, is assembled upon this single wall to be later attached to the box or case in making up the complete machine. The wall I5 is thus adapted to be mounted at the front of the case resting upon the base extension 25 and is adapted to support or have secured thereto a plurality of fihn guide rollers 26 of any suitable number which may be extended indefinitely according to the length of film to be exposed as thus supported. These rollers are supported by bolts or stud shafts 21 extending out horizontally from the wall at right angles and secured thereto as by lock screws 28 with suitable spacing sleeves between the rollers and the wall. As shown, these rollers are fixed and three upper rollers and two rollers are illustrated, the forward upper roller being consider ably spaced from the two pairs of upper and lower rear rollers so that the film may be passed around the same in serpentine form or as a continuous loop with suitable means for taking up slack according to the length of the film. An adjustable horizontal lower guide roller 29 is also provided on the wall |5 near the base extension 25 at the front and is mounted on an adjustable stud 30 secured to the wall l5 and having a knurled finger piece or knob in the form of a nut 3| which engages a flanged nut or a locking plate 32 at the back of the plate I 5 after passing through the latter. The flanged nut is provided at the back of an elongated horizontal slot 33 in the wall l5 and the flanged nut 32 preferably has fiat faces adapted to engage the elongated slot 33 and above and below with a portion projecting im to the slot at the hub to take the reduced end of the shaft so as to support the roller in a true horizontal position together with the knob thereon. A similarly mounted vertical adjustable roller 34 is mounted between the upper and lower pairs or series of rollers 26 at the back, it being understood that the number of rollers 28 may be varied according to the length of the fihn as previously explained. This roller 34 is mounted on and secured to the wall l5 by an adjustable stud shaft or bolt 35 having a knurled knob portion 36 and the stud shaft being provided with a flanged nut 31 having fiat faces adapted to engage an elongated vertical slot 38 formed in the wall I 5 with portions engaging on opposite sides of the slot through the medium of the flanged nut 31 at the back in the same manner as the bolt or stud shaft 3|! or adjustment to tension or take up slack in the fihn in the manner shown in Fig. 1 of the drawings.

A fihn feeding sprocket roller 39 having sprocket teeth 40 is secured to a shaft 4| which extends through the wall l5 and is provided with a feeding cam or star wheel 42 secured thereto by a set screw 43. A hand operating knurled knob 44 is provided on the shaft 4| and may be secured by threading or a set screw as shown in Fig. 2. An idle guide roller 45 is positioned be neath the sprocket roller 39 so that the film, after passing under the feeding roller, passes over the guide roller and then to the roller 29.

Slightly above and in rear of the sprocket or feeding roller 39, an opening 45 is provided through the wall l5 and a fixed aperture plate 41 is secured vertically across said opening through the medium of flanges 48 on opposite sides thereof held by screws 43. This plate is provided with a rectangular film aperture 50 and upper and lower pair of ears 5| to guide the film. A pressure aperture plate 52 having a similar registering aperture 53 is held against the plate 41 at the back and the latter plate has a forwardly curved upper lip 54 while the plate 52 has a rearwardly curved shorter lip 55 to extend between the upper ears 5| on the plate 41. An apertured pressure spring 56 is provided at the back of the plate 52 and has an aperture 51 to register with the apertures 50 and 53 in the respective plates 41 and 52 and an angular pressure end 58 to engage against the outer portion of the loose plate 52 beyond and above and below the apertures to hold the plates uniformly together or the plate 52 against the fixed plate 41. The opposite or inner end 59 of the spring 55 is turned or curved forwardly and outwardly and has a pair of holes 60 registering with corresponding holes in the plates 41 and 52 to take hollow rivets 6| which are anchored on the plate 41 while the plate 52 and the spring are loose to ride thereon although the spring is held from displacement by upsetting the inner or rear ends of the rivets. The turned end 59 is-adapted to ride on a bent seat 62 provided along the inner edge of the plate 52 and both of the plates 41 and 52 are provided with oppositely pressed channels 63 opposing one another and on opposite sides of the apertures with inwardly pressed ribs 64 which result in a slight spacing of the plates particularly at the apertures so that only the edges of the film engage the plates at such points thereby permitting the film to travel smoothly and preventing obstruction or catching to the overlapped ends of a film strip at such points where the ends of the strip are joined to form a continuous film or at points of mending. In feeding or removing the fihn from between plates, it

is necessary to separate the pivoted plate 52' from i the fixed plate 41 and for this purpose, the pivoted latter is driven, the engagement of the teeth with the holes will advance the film. It is also desirable to remove any dust or foreign matter from the film strip and for this purpose, a pair of brushes 69 are mounted with their bristles in interlocking relation beneath and slightly forwardly of the upper and forward roller 29 and an elastic felt band 19 may be mounted upon the base extension 25 in position to engage the film beneath the lower rollers 29 and 29, thus keeping the film clean to insure clear pictures.

The feeding cam or star wheel 42 constitutes part of a Geneva or star wheel movement to intermittently advance the film between intervals of exposure at any speed desired and, as previously explained, the film may be exposed for seven seconds or three and one-half seconds or for other suitable time intervals between advancements. For this purpose, the feeding cam 42 is provided with teeth 1| the number of which is the same as the pairs of teeth 49 of the film feeding sprocket roller 39 and as the continuous film 99 has a succession of pictures 91 and pairs of sprocket holes 69 which are spaced along the film by the same spacing asthe teeth" of the feed roller 39, the intermittent rotation of the roller 39 is so arranged by the mechanism hereinafter described in conJunction with the teeth 1| of the feeding cam or star wheel 42 to pass the film past the apertures 59, 53 and 51 and register the same therewith or center the picture relative to the film gate aperture as the film is intermittently fed or advanced at equal intervals of time of movement and, while stationary, for exposure. It will also be clear that the roller 29 is so adjustable with or without adjustment of the roller 34 to provide appropriate tension for the film 65 which is an endless unit.

As may be clearly seen from Figs. 8 and 11 of the drawings, the feeding cam wheel 42 is provided with the teeth H, the numberof which is the same as the pairs of sprocket teeth 49, and each tooth 1| has an abutment surface or short edge 12 which is substantially radial and a fiat clearance surface or long edge 13 which is substantially circumferential although both surfaces or edges are somewhat tangential to the periphery. The adjacent surfaces 12 and 13 form notches=or grooves therebetween, the intermediate crotch being of angular formation and controlling by the depth thereof the degree of movement imparted to the feeding cam as will be later described. A centering or friction spring 14 is mounted on one of the screws 49 and extends down from its anchored end on said screw under another one of the screws 49 therebeneath as at 15 and is then formed with an angular or curved end 19 disposed over and against the hub of the cam wheel 42 so as to friction the latter and center the teeth as well as the picture panels or frames 91 with respect tothe film apertures in the film gate as previously described. A crank arm 11 of the driving mechanism or motor unit is provided with a pin 18 extending laterally to engage the abutments 12 past the clearance surfaces 19 and is mounted on a rotatable shaft 19 between frame members 99 forming spaced plates for supporting the motor unit at the lower portion of the front plate or wall I5 at the inside through the medium of posts 9| which engage the wall or panel I9 at one end of the frame 99 and a bracket 92 at the other end, which bracket is also supported by means of bolts or screws-through the front wall or plate l5 forming a panel for the case upon which the mechanism is supported. A pinion 99 of areduction gear train 94 is mounted between the frame members or spaced plates 99 and engages an adjacent gear of the gear train 94. This pinion is mounted on an armature shaft which also carries an armature 99 of a motor 81 also supported by the plates 99 including the usual field magnets and windings or coils if an electric motor is used, or other suitable form of driving or clock mechanism.

The circuit including the motor has a wire 99 leadingv from the motor 91 to a switch 99 on the side Or rear wall I9, although this switch maybe mounted on the end of an extension cord for remote control as is common in the art, if

desired. A wire 99 also leads from the motor to,

a plug socket 9| also shown mounted on the wall I9 for connection with an extension cord from a wall socket or house wiring to supply current. A wire 92 leads from the other side of the switch 99 to the socket 9| and the switch is provided with a lever or button 93. A cross bar 94 may be mounted at the back or side 29 opposite the wall or plate I5, this side being open in the form shown and spanned by the cross bar suitably anchored at its ends to the inturned ends of the walls I9. A fan 99 of the electrical type is mounted upon the cross bar 94 and the armature shaft 99 thereof carries a cooling fan 91 at its inner end directed toward the mechanism previously described. A wire 99 leads from the motor to the socket 9| conjointly with the wire 99 and a wire 99leads from the other side of the motor to the switch 99 conjointly with the wire 99, the switch being suitably insulated from the metal or other material of the case I6 so that by closing the switch both the driving and fan-motor will be placed in operation. The motors may be provided with oiling tubes I99 which for convenience may be led through the top of the case to facilitate oiling the motors.

A bracket |9I is also mounted at the outside of the wall. I5 to support a socket shell I92 in a vertical position to take a projection lamp I93, power for which is supplied by wires I94, and I95, the first of which leads to the socket and the second of which leads to the contact post I99 or point with which the single contact point of the lamp engages. These wires are in turn connected to the wires 99 and 99, respectively, so that the circuit may be controlled by the switch 99 when the motors are placed in operation. A reflector I91 is also mounted on the wall I5 in back of the lamp I99 to reflect the light rays forwardly through a condensing lens system I99 of any suitable design also mounted on the wall I5 and after passing through the film gate aperture to project the picture thereof upon a suitable screen through an obj ctive lens assembly I99 also of any suitable design and constituting a focusing medium. The objective lens assembly I99 is supported by a tubular bracket or split clamp ||9 mounted horizontally at the front of the wall I5 and providedwith a knurled clamp screw III for bringing the spaced portions or jaws of the clamp into frictional engagement with the casing of the objective lens to hold the same in adjusted focusing position A bottom opening H2 is provided in the wall I6 and is shown as a circular opening adjacent the socket of the lamp and the bracket 32 which supports one end of the motor frame 30 and a vertically elongated slot or opening H3 is also provided in the wall I5 adjacent the lamp I63. An opening H4 is provided adjacent the condensing lens system I08 and the opening I I3 communicates with a comparatively wide and substantially semi-circular horizontal opening I II at the top similarly provided through the wall I 5. The purpose of these openings is to permit the air blast from the fan or the cool current thereof to pass through the openings to maintain the adjacent parts in a cool operative condition and avoid inconvenience in handling, as well as combustion of the film by excessive heat. To facilitate this, a detachable hood H6 is mounted over the lamp and lens and, for this purpose, is provided with a forked lug III at the bottom to engage a headed pin II6 projecting from the wall I6 below the opening H2 and has an ear H3 at the top with a headed pin or tapered lug I to engage through an opening I2I in the wall I3 and with a spring catch I22 held between the wall I6 and a plate I23 mounted at the back of the wall over the opening and held by rivets, screws or the like constituting posts I24. These posts, as shown in Fig. 10 of the drawings, support the spring members of the catch I22 and engage behind the headed pin or lug I26 to detachably secure the hood in position over the lamp and lens but to permit convenient removal thereof for obtaining access to said parts or the wire connections to the socket and contact post of the plug held therein and resiliently pressed toward the contact point of the lamp as is usual in such types of lamps and sockets having the usual pins and bayonet slots for securing the lamp bulb in position. The hood H6 is provided with a series of spaced parallel vertical heat dissipating vanes I25 and a plurality of vertical slots I26 similarly related through the wall thereof, the outer slots being shown shorter than the inner slots. A baiile plate I21 is fastened to the hood at the inside in spaced relation to the front portion thereof with suitable posts or spacing screws I23 providing slots I29 at the sides, which sides are closed at the top due to the plate being flat and turned angularly beneath the top portion of the hood while the top portion as well as the bottom portion are relatively concavo-convex. This provides a slot I30 between the plate and the top 'of the hood at the inner or open side thereof so that the current of cool air from the fan passing through the openings H2. H3, H4 and H5 may pass into the hood, around the baiiie plate at the side slots I29 then out through the slots I26 while some of the air will pass out through the slot I30 to the top of the casing to displace the heated air therein. An opening IN is provided in the front vertical wall of the hood H6 in front of the lamp III3 and the lens system I03, the adjacent face of the hood being thickened and slanting or beveled toward the inner surface of said wall preferably as shown in Fig. 9 of the drawings and provided with a groove or seaf I32 to take a suitable glass panel I33 which is held by 5: lug I34 at the outside and a sheet metal clip I36 at the inside, which clip is held in position by a screw or other suitable means to render it detachable. A hood 75 I36 is provided at the inside of the case on tlm wall I5 in back of the hood H6 and the openings through the wall I5 and tapers downwardly in general form with an inclined inner and bottom wall I31 and an enlarged top portion I33 disposed beneath the top opening 22. At the top portion of the hood I36 is a baiiie frame I33 having a plurality of inclined parallel bafile plates I40 to deflect the air toward the back of the case above the top thereof and away from the wall I3 and parts mounted thereon as previously described. It is, of course, to be understood that the hood I36 is closed at the sides as well as at its inner side and bottom and beneath the enlarged top portion I38 and is formed with a cutout I4I communicating with the opening II4 adjacent the condensing lens system and bracket Ill so that the heat of the lamp will be deflected out through the same to escape at the top of the inner hood I36 after being forced by the fan through the bottom opening II 2 and then upwardly around the lamp andlens system within the outer hood II6, thereby maintaining these parts in a cool and efllciently workable condition.

With the star wheel or Geneva movement previously described using a single arm II which engages the abutment edges I2 of the teeth of th feeding cam 0r star wheel 42 at each revolution of the shaft I9 driven by the motor I! through the gear train or clock mechanism 34, there is an intermission say of seven seconds between each advancing motion during which the picture is projected and exposed, the advancement taking place intermittently after each exposure. In order to reduce this time duration of exposure, say one-half, a cross arm I42 may be employed as shown in Fig. 13 of the drawings in lieu of the single arm I1. This cross arm is similarly mounted upon the shaft 19 and each arm has a similar pin I3 for engagement with the teeth of the cam each complete revolution. In this way, the time exposure may be reduced to three and one-half seconds between intermittent intervals of advancement.

In the operation of the picture or advertising projecting machine as above described, the film strip is fed around the various rollers and through the film gate between the pressure plates 41 and 32 so as to pass and properly register with the The switch is then closed to the motors and lamp to cause the light rays to be projected through the picture so that the latter will be projected upon a screen and successively advanced along for display and advertising pur- As the motor 31 is operated, the crank 11 will be driven through the clockwork or reduction gear 34 to cause the advancing of the film intermittently by reason of the pin I3 striking the abutment edges or surfaces I2 of the star wheel or feeding cam 42 of the intermittent feed formed by the Geneva movement. The pin I3 will enter the notches of the star wheel and advance the same one tooth at each revolution of the crank arm 11 with its shaft I3, passing out over the clearance surfaces or edges I3 and the friction of the spring 14 against the hub of the feeding cam 42 will not only cause uniform movement thereof, but check the movement of the film after the arm is passed out of a notch and serve to intermittently hold the wheel against rotation as well as center the pictures or advertising matter in the frames or panels of the film relative to the film gate aperture at all times crank is'fotated. In this way,

centeringspring serves as a brake and insures uniform feeding or advancement of the film.

By. way of example, it will take approximately eight seconds for the crank arm 11 to rotate acomplete revolution, one second qfwhichis usedin'advanc'ing the film a complete frame or panel so as to'present a different picture or advertising panel 61 -to view from the film 6G through'the apertureifl and the same exposed ffor seven seconds of time, which will ordinarily be sufiici'ent for the purpose for whichthe maj chine has been designed, which'willbe for ad- I vertising or other display purposes. 'However, it may be used for ordinary picture projection and with a film of 130 frames, it will take approxias previously described. In feeding the film through the film gate, it is only necessary to press rearwardly on the finger lip or extension 65 of the pressure plate 52 so that the film may be radially passed between the plates including the fixed aperture plate 41 and the pivoted pressure plate 52 to be held by the spring 56 upon release of the plate 52. It will also be seen that manufacture is greatly facilitated by reason of the mounting and assembly of most of the mechanism upon a single wall or plate forming the panel i of the case and that all of the parts are readily accessible for adjustment, repair or replacement. The cooling device will maintain the parts in a cool and highly desirable condition so as not to injure the film as well as to facilitate handling thereof by the operator, when necessary.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, this is capable of variation and modification without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such vari ations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to claim by Letters Patent is:

ll The combination with a picture projector having a light source,'lenses, and a film gate, of means to advance the film through said gate, said means including a driving sprocket and a toothed star wheel therefor, a crank having an arm adapted for intermittent engagement with said star wheel to advance the film one picture panel for each tooth of the star wheel for still exposure each interval between each engagement, and a motor drive for said crank, said teeth having substantially radial abutment faces and substantially circumferential clearance faces for the crank, said star wheel having spring brake means.

2. The combination with a picture projector having a light source, lenses, and a film gate, of means to advance the film through said gate, said means including a driving sprocket and a toothed star wheel therefor having a smooth peripheral portion, a crank having a pin adapted for intermittent engagement with said star ,wheel, and a motor drive for said crank, said the and substantially circumferential clearance faces,

said faces" adapted to form grooves'to clear the crank, and a locking spring adapted to frictional- 1y en age said smooth'peripheral portion..

3. The combination with a picture projector havinga' light source, lenses, anda film gate, of means toadvance the film through said gate,

said means including a-"driving sprocket and a toothed star wheel therefor having a circular hub, a double crank having pins adapted .for intermit- I tent engagement with said star wheel, and a motor drive for said crank-,' said teethliaving substantially radial abutmen't faces and substantially circum1" =:rential clearance' faces, said mately '15 minutes to expose and project the enfaces-adapted to form grooves. to clear the crank, and a locking spring adapted to engage said hub to friction .and hold the advancing'means between advancements'to' center the'frames'o'f the film relative to the film gate, said spring having a curved portion adapted to engage and fit the periphery of said hub.

4. The combination with a picture projector having a light source, lenses and a film gate having an aperture, of means to advance the film through said gate, said means including a driving sprocket and a toothed star wheel therefor having the same number of teeth as the sprocket and a hub with a smooth peripheral face, the teeth of said star wheel having substantially radial abutment faces and substantially circumferential clearance faces, said faces adapted to form indexing grooves to advance the film one panel for each tooth, a crank adapted for inteeth having substantially radial abutment faces termittent engagement with said radial faces of the star wheel, a motor drive for said crank and an indexing spring for said star wheel adapted to engage said hub to center the film panels relative to the film gate aperture and friction the rotation of the star wheel to cause even and uniform advancement of the film and check the movement of the film when centered at each exposure.

5. In a picture projector, a film gate, means to advance the film through said gate, said means including a feeding cam wheel and a toothed wheel therefor, a crank arm having a lateral pin adapted for intermittent engagement with said toothed wheel and a motor with a gear train drive means for said crank, said cam wheel having a circular portion and means to frictionally engage and fit said circular portion.

6 .A picture projector including a film gate, means to advance the film through said gate including a feeding cam wheel and a toothed wheel mounted to rotate therewith, an arm having a lateral pin adapted for intermittent engagement with the teeth of said wheel as the arm is driven, said cam wheel having a cylindrical portion and a frame centering spring having a curved portion disposed over and aga nst said cylindrical portion.

7. In a picture projector, a film gate, means to advance the film through said gate, said means including a driving sprocket having a shaft, a beveled toothed wheel fixed to the shaft and having the same number of teeth as the sprocket, a crank having one or more pins adapted for intermittent engagement with the teeth of the wheel to advance the film one picture panel for each tooth for still exposure between each engagement and means for driving the sprocket and wheel, the depth of the notches of the toothed wheel controlling the degree of movement imparted thereto.

8. A picture projector including a film gate means to advance the film through said gate,

- said means including a film ieeding roller and a toothed cam wheel therefor having a circular portion and the same number of teeth as the roller, a crank having an arm adapted for intermittent engagement with the cam wheel and a spring adapted to engage the circular portion for guiding the film through the film gate,'means to advance the film through the gate at said side, means mounted at the opposite side of the wall to operate said film advancing means, a

to friction and hold the-advancing means between advancements to center the irames of the film relative to the iilm'gate.- v

9. In a picture projector, a case, asingle removable vertical wall forming one side of the case and having openings therein communicatalso supported on the same side of the wall between and in alignment with the lenses, rollers removable hood over said light source with outlets at. thetop of the case and at the front of the hood, a hood against. the top portion oi the wall within the case and having an open side toward the caseand over the openings in the wall and open at the top, said latter hood also having a closed inclined side opposite the open side and wall, closed front and rear walls and baiiies beneath the top opening and a corresponding opening in the top of the case, and a cooling fan beneath said inclined side to blow air through. the wall, hoods and around the light source and lenses.

Y JOSEPH GUERCIQ. 

